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April 16, 1929. c. NEWMAN ET AL 1,709,187

KNOCK OUT FOR SWITCH BOXES AND THE LIKE Filed Sept. 12, 1927 QMHIHHH mm 15 45 1/ 17 'V/l/KIIIIIIIIUW/l/l/A V nmmm A e.

y fade/257;?- Cfazrlba/vcwr/zarz, Mew-- fi ew/mf 9 M A -q I if/45! Gaga/52 5% Patented Apr. 16, 1929.

UNITED STTES aren't] OFFICE.

CHARLES NEWMAN, OF NEW YORK, N- Y., AND ERNST G. APPLETON, OF CHICAGO,

ILLINOIS, ASSIGNOBS TO ROACH-APPLETON MANUFACTURING COMPANY, OF CHI- CAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

KNOCK-OUT FOR SWITCH BOXES AND THE LIKE.

Application filed September 12, 1927. Serial No. 218,934.

The present invention relates to improve ments in knockouts for switch boxes and the like.

It is common practice in electric house wiring to provide receptacles into which the wires of an electric house wiring system are brought, said wires commonly being enclosed within conduits. Said conduits may be presented to a switch box or similar device from a great variety of angles. Switch boxes or similar devices have been provided with portions termed knockouts which may be readily removed by the electrician on the job. Said knockouts are commonly circular in outline to conform to the usual contour of conduits and are defined by partial perforations. As heretofore constructed, knockouts have commonly been either substantially flush withthe material of the switch box or similar receptacle or have been pressed slightly inwardly whereby the workman, with any convenient tool, may knock the knockout inwardly of the receptacle. In removing the knockout, it frequently happens that a rough edge is left.

Frequently workmen'have cut their hands upon such rough edges and the cuts have sometimes ledto very serious consequences. It is common also to provide clamps within the. switch boxes or similar receptacles, for

holding the extremities of the conduits seourely in place. Said clamps are frequently positioned in obstructing relationshlp with the knockouts and the workman must insert his fingers into the receptacle and hold said clamps out of such obstructing relationship. Under these circumstances, the workman when he drives the knockout inwardly very likely to injure his fingers.

An object of the present invention is to provide a switch box in which the knockout-s may be pried outwardly, thereby a void ing danger to the hands of the worknnin.

A further object is to provide a switch box or similar receptacle from which knockouts may be removed withoutregard to clamps, or other devices, within said switch box or other receptacle.

Further objects will appear as the description proceeds. Referring to the drawings;

Figure 1 is a view in front elevation of a switch box embodying the principles of the present invention.

Figure 2 is a View in end elevation of the structure in Figure 1.

Figure 3 is a sectional view taken along the plane indicated by the arrows 3-3 of Figure 1.

Figure 4 is a view in elevation of a portion of a switch box showing a modification.

Figure 5 is a sectional view taken along the plane indicated by'the arrows 5-5 of F igure 4.

Figure 6 is a sectional view taken along the plane indicated by the arrows 66 of Figure 4:.

Figure 7 is a View in elevation of a portion of a switch box showing another modification.

Figure 8 is a sectional view taken along the plane indicated by the arrows 8-8 of Figure 7. A

Figure 9 is a sectional view taken along the plane indicated by the arrows 99 of Figure 7. I V

The numeral 10 indicates a switch box, which may be taken as typical of receptacles of electric conduits. Said switch box 10 is .provided with a plurality of knockouts the box. The extent to which said knockouts are pressed outwardly is not material but at least a portion of such knockouts should be disposed outwardly a sufficient distance to permit prying relationship therewith, without leaving large openings through which sparks may pass in the event of sparking within the switch box.

of the screw driver, or similar tool.

Said knockouts 1l11, which lie in substantially parallel relationship with the corresponding wall oi the switch box, are defined by partial perforations l t-le which partial perforations are preferably circular in outline to conform to the usual circular outline of conduit. Said partial perforations Pia-14iare interrupted at the intact portions 15, which intact portions constitute hinges, when the knockouts 11 are pried loose from the remainder of the switch boX, and which may be readily broken off when the knockout is being removed.

In order to permit the knockouts to be pried loose from the switch box, the peripheral edge portion of each of the knockouts, according to the embodiment of the invention disclosed in Figures 1 to 3, is provided with one or more notches 16-l6. Said notches 16-;16 will be of sutlicient size to permit a screw driver to be used in prying loose the corresponding knockout.

In the embodiment oi": the invention appearing in Figures l, 5, and 6 an edge portion of the knockout 11 is bent outwardly of the box to permit engagement of a screw driver or similar tool to permit a prying action. The edge portion referred to is indicated in Figures 4, 5, and 6 by the numeral 17.

In the embodiment of the invention appeering in Figures 7, 8, and 9 only a small portion of the periphery of the knockout 11 is swedged outwardly to permit engagement The swedged out portion in Figures 7, 8, and 9 is indicated by the numeral 18. v Though the present invention has been illustrated inconnection with switch bones it is also applicable to outletboxcs, covers, stamped metal boXes, neter boxes, and other "receptacles provided with knockouts tor the recept on of condult. Referring particularly to meter boxeait will be obvious at once that the knockouts whichmay be pried outwardly are a great help to the contractor and that a vast saving in time accrues due to the ease with which he may )ry the knockouts from outside of the box instead of itrom w1th1n' the box. In this conncctionit may be pointed out that the matter of removing the knockouts according to the present invention does not that in removing a knockout itis not necessary for workmen to put their fingers into the box in the operation or removing said knockout.

'lhough certain preferred embodiments of the present invention have been described in detail, many modifications will occur to those skilled in the art; itis intended to cover. all such modifications that fall within the scope of the appended claims.

What is claimed as new is 1. In aswitch box in combination, a wall portion having a knockoutassociated therewith, said knockout being defined by a par tial perforation interrupted by a single intact portion adapted to operate as a hinge, said knockout being disposed in substantial parallel relationship with said wall portion, the edge portion of said knockout being formed with means for engagement with a prying tool outwardly oitsaid box. l

2. A receptacle having a wall portion provided with a knockout, said knockout being defined by a partial perforation interrupted by a single intact port-ion adapted to operate as a-hinge, said knockout being disposed in substantial parallelism with said wall portion, the edge portion of said knockout being formed with an abutment tor the reception or" a prying tool. 7,

8. A switch box having a wall portion provided with a, knockout, said knockout being defined by a partial perforation which partial perforation is interrupted by a single intact portion, said knockout being formedopposite to said intact portion with abutment means for the reception of a prying tool.

t. A receptacle having a wall portion provided with a knockout, saidknockout being defined by a partial perforation and being disposed outwardly of said box, said'partial perforation being interrupted by a singe intact portion, an edge portion of said knockout opposite to said "intact portion being,

termed with abutment means for the reception oi a prying tool.

5. In a switch box, in combination, a wall portion having a knockout swedgcd therefrom in parallel relationship with said wall portion, said knockout being circular in outline and being defined by a circular line of rupture interrupted on one side only of said circular line by an intact portionadapted to operate as a hinge, the portion of said knockout opposite to said intact portion being formed with means for engagement with a prying tool.

6, In a switch box, in combination, a wall portion having a knockout swedged therefrom in parallel relationship with said wall portion, said knockout being circular in. outa line and being defined by a circular line of I rupture interrupted on one side only of said circular hne by an intact portion adapted to V operate a hinge, the portion ofsaid knock out opposite to said intact portion being formed With a notch in its periphery for the reception of a prying tool.

7. A switch box having a Wall portion provided With a knockout, said knockout being defined by a partial perforation having the outline of a geometrical figure but interrupted by an intact portion on one side of said geometrical figure, said knockout being formed opposite to said intact portion with a 10 notch in its edge portion for the reception of a prying tool.

Signed by CHARLES NEWMAN at New York, New York, this 23rd day of August, 1927, and by ERNST G. APPLETON, at Chicago, Illi- 15 nois, this 31st day of August, 1927.

CHARLES NEWMAN. ERNST G. APPLETON. 

